Faxlogic? Anyone tried it?

Currently we have 4 fax lines at different locations that might get used to send 15 faxes a month. The cost of these lines adds up to $2,000 a year. We already have the multifunction printers with faxes in place, has anyone tried faxlogic's fax line replacement plans? http://www.faxlogic.com/pricing/classic-fax-machine-line-replacement-plans-and-pricing.php.